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镁热还原法制备圆片状氮化硼多晶微粉 总被引:1,自引:1,他引:0
采用三氧化二硼(B2O3)、氯化铵(NH4Cl)和镁粉为反应物, 以三氧化二铁(Fe2O3)为催化剂, 利用镁热还原法在700~850 ℃下反应, 制备了氮化硼多晶微粉. X射线衍射(XRD)分析表明, 产物为六方相, 晶格常数a=0.2499 nm, c=0.6682 nm. 产物的红外光谱中在790和1380 cm-1处出现了六方氮化硼的特征吸收峰. 利用扫描电子显微镜(SEM)观察到产物为圆片状颗粒, 平均直径约为0.9 μm, 平均厚度约为100 nm. 讨论了Fe2O3的存在对产物形成的影响. 相似文献
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利用水热法合成了立方氮化硼(cBN). 通常水热法制备的氮化硼样品是立方氮化硼(cBN)和六方氮化硼(hBN)及其它晶相的混合物,这限制了该方法的应用前景. 文中利用立方氮化硼在特定反应条件下的自发团聚现象,成功地发展了一种使混合物中的立方氮化硼在反应过程中自发纯化的新方法. 提高原料浓度和反应温度,有利于获得更大粒径的立方氮化硼和尺寸分布更均匀的团聚颗粒,提高搅拌转速来改善溶液的均匀性也有同样效果;而提高反应压力则会导致相反的结果. 文中也探讨了自团聚现象在生长大尺寸立方氮化硼晶体以及非均相合成中的潜在应用价值. 相似文献
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采用电沉积法,在阳极氧化铝(AAO)模板中制备了[NiFe/Cu/Co/Cu]n多层纳米线.利用扫描电子显微镜(SEM)及透射电子显微镜(TEM)对纳米多层线的表面形貌及结构进行了表征,纳米线阵列高度有序、直径均一、层状结构清晰,NiFe层厚度约40 nm,Cu层厚度约60 nm,Co层厚度约15 nm,各子层厚度可控.利用X射线能谱分析仪(EDS)对纳米多层线NiFe层的成分进行了测试,Ni,Fe的原子比为4:1.利用X射线衍射仪(XRD)对[NiFe/Cu/Co/Cu]n纳米多层膜和多层线结构进行了测试,多层膜为面心立方(fcc)结构,多层线NiFe层为面心立方(fcc)结构,Cu层为六方密排hcp(100),Co层为面心立方(fcc)结构.与组成、结构完全相同的多层膜相比,[NiFe/Cu/Co/Cu]n多层纳米线具有更优越的巨磁电阻性能. 相似文献
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以无水氯化钴(CoCl2)为催化剂, 采用氧化硼(B2O3)和氯化铵(NH4Cl)为反应原料与镁粉在密闭反应釜内发生镁热还原反应合成了亚稳态立方氮化硼(e-BN)多晶粉. 产物粉末的X光衍射(XRD)分析表明晶格常数a=0.8304 nm, 红外光谱(FTIR)在500, 650, 797, 1085, 1374和1580 cm-1有特征吸收峰. 扫描电子显微镜(SEM)观察到产物为近似球状颗粒, 平均直径为70 nm, 粒径均匀. 讨论了化学反应和产物在催化剂作用下的形成机理. 相似文献
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利用X射线衍射(XRD)、拉曼光谱(Raman)、X射线光电子能谱(XPS)和交流阻抗谱对溶胶-凝胶法制备的稀土双掺杂固溶体Ce0.8Cd0.2-xPrxO1.9(x=0,0.02,0.10)的结构和导电性进行了研究.XRD结果表明,经800℃焙烧所得样品都形成了单相立方萤石结构,平均晶粒尺寸在23~30 nm之间;X... 相似文献
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Starch/boron nitride (starch/BN) bionanocomposites were prepared with the reinforcement of boron nitride nano powder by solution technique. The dispersion of BN in the starch was achieved by a continuous sonication process. The interaction between starch and boron nitride nanopowder was investigated by Fourier transform infrared (FTIR) spectroscopy. The structural properties of starch/BN bionanocomposites was studied by X-ray diffraction (XRD). The high resolution transmission electron microscopy (HRTEM) was used for the study of dispersion of boron nitride in starch matrix and diffraction patterns were studied by selected area electron diffraction (SAED). Thermal stability of the starch was increased with rising concentrations of boron nitride due to incorporation of rigid nano BN with starch matrix. The substantial reduction in oxygen permeability was obtained by increasing the concentration of BN. The biodegradability of synthesized bionanocomposites was measured by using activated sludge water. Further, it was noticed that, starch/BN bionanocomposites are resistant towards inorganic acids and bases. The tensile strength of starch/BN bionanocomposites was increased whereas; the water resistance property of the materials was decreased with increasing BN loading. 相似文献
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Benno Lux Roland Haubner Martina Griesser Manfred Grasserbauer 《Mikrochimica acta》1997,125(1-4):197-209
In the development of diamond and c-BN products the analytical methods for characterizing the surface, bulk and interface of the diamond coatings are very important. SEM, Raman, XRD and IR are the methods used for characterization and SIMS, TEM, AES, NRA, RBS, XPS, STM, etc. are used for the investigation of special problems. The techniques for diamond and c-BN production are briefly summarized to give an idea of the complex interactions between production, application and analytical characterization. The analytical methods for diamond characterization and many relevant results are summarized in this paper; some physical properties (e.g. thermal conductivity, transparency, etc.) and their interaction with applications are also discussed.Abbreviations AES
Auger electron spectroscopy
- AFM
atomic force microscopy
- c-BN
cubic boron nitride
- CL
cathodoluminescence
- CVD
chemical vapour deposition
- EELS
electron energy loss spectroscopy
- EPMA
electron probe microanalysis
- ERDA
elastic recoil detection analysis
- h-BN
hexagonal boron nitride
- HP-HT
high-pressure high-temperature
- HF
hot-filament
- IR
infra-red
- LEED
low energy electron diffraction
- MW
microwave
- NAA
neutron activation analysis
- NRA
nuclear reaction analysis
- PL
photoluminescence
- PVD
physical vapour deposition
- RBS
Rutherford backscattering spectrometry
- RHEED
reeflected high energy electron diffraction
- SAD
selected area diffraction
- SEM
scanning electron microscopy
- SIMS
secondary ion mass spectrometry
- STM
secondary ion mass spectrometry
- TEM
transmission electron microscopy
- TMB
trimethylborate
- XPS
X-ray photoelectron spectroscopy
- XRD
X-ray diffraction
Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday 相似文献
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Liang-xu Lin Ying Zheng Zhao-hui Li Xiao-nv shen Ke-mei Wei 《Solid State Sciences》2007,9(12):1099-1104
Hexagonal boron nitride (h-BN) fibers with polyhedral morphology were synthesized with a simple-operational, large-scale and low-cost method. The sample obtained was studied by X-ray photoelectron spectrometer (XPS), electron energy lose spectroscopy (EELS), X-ray powder diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), etc., which matched with h-BN. Environment scanning electron microscopy (ESEM) and transmission electron microscope (TEM) indicated that the BN fibers possess polyhedral morphology. The diameter of the BN fibers is mainly in the range of 100–500 nm. 相似文献
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Cubic boron nitride (cBN) and orthorhombic boron nitride (oBN) crystals have been prepared in hydrothermal solutions by reacting H3BO3 NaN3 P and H3BO3 NaN3 N2H4 respectively. The experimental results indicated that, if the temperature was increased rapidly, both the yield and perfectness of BN crystals became poor. On the contrast, the yield and perfectness of BN crystals can be improved very much by slowly increasing the temperature of the reaction mixture. The results of X-ray powder diffraction (XRD), Fourier transform infrared spectrum (FTIR) and high resolution transmission electron microscopy (HRTEM) proved that the samples were composed of oBN and cBN. 相似文献
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A. N. Streletskii D. G. Permenov K. A. Streletzky B. B. Bokhonov A. V. Leonov 《Colloid Journal》2010,72(4):544-552
The regularities of the mechanical activation of hexagonal boron nitride are analyzed using the X-ray diffraction, IR spectroscopy,
transmission electron microscopy, dynamic light scattering, and adsorption methods. At the initial state of mechanical activation,
the main process is material destruction. At this stage, the specific surface area increases to 400 m2/g and crystallographically oriented nanosized needles are formed. At the same time, boron nitride crystal structure is disordered
with an increase in interplanar distance d(002). The disordering is assumed to be due to a shift along planes (001). At a specific dose of supplied mechanical energy
above 6–8 kJ/g, the disordering processes dominate and the material is amorphized. At this stage, the specific surface area
of samples decreases. 相似文献
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Nanocrystalline boron nitride (BN) with needle-like and hollow spherical morphology has been synthesized by nitriding of MgB2 with NH4Cl and NH4Cl-NaN3, respectively. The amount of NaN3 has an obvious effect on the size of the hollow spheres. The samples were characterized by X-ray powder diffraction, Fourier transformation infrared spectroscopy, X-ray photoelectron spectra, and transmission electron microscopy. The possible mechanism of morphology control is also discussed. 相似文献
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A. N. Streletskii D. G. Permenov B. B. Bokhonov A. V. Leonov S. N. Mudretsova 《Colloid Journal》2010,72(4):553-558
Mechanical activation makes boron nitride chemically reactive with respect to water. The fact of the reaction proceeding,
which is accompanied by a change in the structure of boron nitride, is confirmed by the data of IR spectroscopy, X-ray diffraction,
transmission electron microscopy, differential thermal analysis, adsorption, and gravimetry. It is established that the most
defective amorphous part of the material is primarily hydrolyzed. The reaction takes place at room temperature, with the conversion
increasing to values of higher than 50% with the dose of mechanical energy supplied during the mechanical activation. In addition
to ammonia, hydrolysis gives rise to the formation of ammonium pentaboride, NH4B5O6(OH)4 · 2H2O. After the reaction products are removed, residual boron nitride, which is dried at T ≤ 100°C, crystallizes to form nanosized rods. 相似文献
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P.W. ZhuY.N. Zhao B. WangZ. He D.M. LiG.T. Zou 《Journal of solid state chemistry》2002,167(2):420-424
We present low stress cubic boron nitride (cBN) films with a transition layer deposited on the metal alloy substrates by tuned substrate radio-frequency magnetron sputtering. The films were characterized by Fourier transform infrared spectroscopy and transmission electron microscopy (TEM). The IR peak position of cubic boron nitride at 1006.3 cm−1, which is close to the stressless state, indicates that the film has very low internal stress. The TEM image shows that pure CBN phase exists on the surface of the film. Several phases of boron nitride were found at the medium implantation dose. It is believed that the transition from the low ordered phases to cBN phase occurred during implantation. 相似文献
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Synthesis and characterization of boron nitride sponges as a novel support for metal nanoparticles 总被引:2,自引:0,他引:2
This paper describes a simple synthetic route for the synthesis of hexagonal boron nitride (h-BN) powders with high specific surface area, in which BBr3, NH4Cl and Al powders are used as starting materials. The structure and composition of the powders were characterized by electron diffraction, Fourier transformation infrared spectroscopy and X-ray photoelectron spectroscopy in the selected area. X-ray diffraction shows wide peaks of crystalline h-BN with the particle size on the nanometer scale, and transmission electron microscopy reveals that the products have a novel spongy morphology. Silver nanoparticles loaded h-BN sponges were prepared via a one-step synthesis method. Different reaction conditions for the formation of h-BN sponges were also investigated. 相似文献
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Bamboo-like multiwall boron nitride (BN) nanotubes were synthesized via annealing porous precursor prepared by self-propagation high temperature synthesis (SHS) method. The as-synthesized BN nanotubes were characterized by the field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD), Raman and Fourier transform infrared (FTIR) spectroscopy. These nanotubes have uniform diameters of about 60 nm and an average length of about 10 μm. Four growth models, including tip, base, based tip and base-tip growth models, are proposed based on the catalytic vapor-liquid-solid (VLS) growth mechanism for explaining the formation of the as-synthesized bamboo-like BN nanotubes. Chemical reactions and annealing mechanism are also discussed. 相似文献